The present invention relates to an information processor using a disk memory having a disk in the form of a portable recording medium capable of being subjected to operations of reading, writing, erasing, and/or overwriting and being disposed in a thin rectangular card-shaped case, and to the disk memory as used therein.
A recording medium which performs read/write of information while being rotated in a card-shaped case, such as an optical disk and a floppy disk, using a tellurium alloy, and being disposed in a flat space between coating materials, is described in JP-A-60-79581.
A magneto-optical disk memory device capable of overwriting by laser power modulation is described in JP-A-62-175948, but a permanent magnet for initializing the magneto-optical disk and a permanent magnet for writing are fixed to the optical disk memory device, and furthermore, an optical head is positioned on the opposite side of the magneto-optical disk from the permanent magnets. Moreover, in the magneto-optical disk, the optical disk medium is made to fixedly adhere onto a substrate having a thickness of approximately 1.2 mm so as to have light incident from the substrate side as a countermeasure against dust attaching thereto, and the optical disk is contained in a protective case for transportation, thus requiring a thickness of 6 to 10 mm for the overall optical disk memory device. Because of the fact that the substrate requires a thickness of 1.2 mm and the permanent magnet for initialization and the permanent magnet for recording are fixed on the side of the optical disk opposite the optical head in a conventional magneto-optical disk as described above, the thickness of this permanent magnet portion is added to the overall thickness of the device, thus not only making it difficult to miniaturize the optical disk, in particular to form it in a credit card size, but also limiting the ability to form a thin optical disk memory device.
On the other hand, a disk magneto-optical medium capable of overwriting on a glass substrate, having a thickness of 1.2 mm incorporated in a cartridge, a permanent magnet for application of an initializing auxiliary magnetic field incorporated in the cartridge, and a permanent magnet for recording installed in a recording device, is disclosed in JP-A-64-46247. However, it is difficult to miniaturize and make thin an optical disk, in particular to form it in a credit card size, when the cartridge is included, because a thickness of 1.2 mm is required for the substrate. Further, since the permanent magnet for recording is fixed on the opposite side of the disk with respect to the optical head, the thickness of this permanent magnet portion is added to the overall dimension of the unit, and thus, there has been a limit on how much the optical disk memory device can be made thinner. Moreover, there is also a problem in that the laser portion of the optical disk is liable to be damaged because the optical disk is exposed when the window of the cartridge cover is opened.
When a disk capable of operations of reading, writing, erasing, and/or overwriting by laser power modulation is used as a memory for a lap top computer or other type of portable information processor, it is desirable for the disk to be rectangular in configuration and to be in a card form or a sheet form from the point of view of thickness and to be provided with a protective case from the viewpoint of portability. In a conventional optical disk, however, because of the fact that the substrate requires a thickness of 1.2 mm as a countermeasure against dust, and particularly in the case of magneto-optical recording, the permanent magnet for initialization and the permanent magnet for recording are fixed on the opposite side of the optical disk with respect to the optical head. Thus, the thickness of this permanent magnet portion is added to the overall thickness of the device, which creates a limit on the formation of a thin film, and so it has been impossible to use such a conventional optical disk in a lap top computer or in a portable optical disk memory device.